The invention relates generally to cold spray and, in particular, to the methods of cold spraying feedstocks including nickel-base alloys.
Bonded surface layers are desired for many applications including those in which the surfaces experience corrosion, erosion, or high temperature. One method used for producing bonded metallic coatings on substrates is cold spray technology. In cold spray technology (also referred to herein as simply “cold spray”), particles are mixed with a gas and the gas and particles are subsequently accelerated into a supersonic jet, while the gas and particles are maintained at a sufficiently low temperature to prevent melting of the particles. Copper coatings have been deposited using cold spray in which sufficient bonding was achieved to produce bulk-like properties. However, higher temperature materials such as stainless steel, nickel, nickel-based and titanium-based super alloys, are likely to require higher velocities to produce high quality deposits with limitations of conventional cold spray devices. In particular, achieving higher particle and deposit temperatures and/or velocities would be desirable.
In order to attain better properties using higher melting point metals than copper, cold spray equipment is moving towards higher gas temperatures. However, even high temperature nitrogen gas is difficult to accelerate to velocities fast enough to make dense deposits of high-melting point materials such as nickel, iron, or titanium alloys. Therefore, in order to have high enough velocities to make dense deposits of the high-melting point materials, helium gas is favored compared to the conventional nitrogen gas. However, using helium gas for cold spraying is commercially challenging.
Therefore, there is a need for an economical method of making a good quality bonded deposit of high-temperature melting alloys.